For more than 3500 years, urinary catheters have been used to drain the bladder when it fails to empty. For people with impaired bladder function and for whom the method is feasible, clean intermittent self-catheterization is the optimal procedure. For those who require an indwelling catheter, whether short- or long-term, the self-retaining Foley catheter is invariably used, as it has been since its introduction nearly 80 years ago, despite the fact that this catheter can cause bacterial colonization, recurrent and chronic infections, bladder stones and septicemia, damage to the kidneys, the bladder and the urethra, and contribute to the development of antibiotic resistance. In terms of medical, social and economic resources, the burden of urinary retention and incontinence, aggravated by the use of the Foley catheter, is huge. Therefore, there is an urgent need for the development of an alternative to the indwelling catheter system.
Post-Operative Urinary Retention (“POUR”) syndrome resulting from anesthesia, and urinary retention from other causes (atonic bladder, spinal cord injury, etc.) requires transurethral bladder catheterization. The catheterization required can be intermittent (single or repetitive straight caths) until the anesthetic wears off over time, or patient ambulation and activity restores normal muscular and postural feedback mechanisms for urination. Alternatively an indwelling/longer term catheter may be required for situations that require more than several hours to return to normal mechanisms or are permanent in nature. The risks and complications known to accompany urinary catheterization are many and can be mild or life threatening. The longer the catheter is in place the greater the likelihood of complication, particularly urinary tract infection (“UTI”)
Bladder catheterization is also a commonly used procedure during inpatient or outpatient major or minor surgery to facilitate monitoring of critical vital signs and data such as urine output, intravenous fluid and volume replacement needs during the perioperative and intraoperative periods. Monitoring urine output, (requiring catheterization) often serves as a surrogate marker of hemodynamic stability. The increase in outpatient and fast-track surgical procedures, makes it much more difficult to obtain this vital monitoring data due to the associated shortened time frames for available intraoperative and postoperative observation prior to home discharge. Holding the patient in the hospital setting because of failure to void spontaneously for whatever reason is an economic issue causing increased global healthcare system costs. It has become one of a number of first line quality of care criteria being used to establish re-imbursement penalties and organizational performance and quality ratings. This issue, combined with catheter associated complications, makes providers reluctant to catheterize patients, despite the fact that the data obtained is still required to monitor the patient's safety and recovery. Urethral catheterization is restricted to fewer procedures and for a much shortened period of time. There currently are no alternatives to catheterization that are safe and provide the combination of monitoring bladder volume together with a way to cause bladder voiding non-invasively (i.e., without catheterization).
The present invention solves these problems by eliminating the need for catherization.
Urinary incontinence (UI) is a second extremely common genitourinary system problem in search of a simple, non-invasive solution. Although standard treatment for UI does not involve catheterization, the problems with abnormal muscular function and neurologic control causing the symptoms can be alleviated by the invention described herein.
The bladder is composed of a body formed by the detrusor muscle and a funnel-shaped neck. The neck has an internal layer of smooth muscle that surrounds the internal meatus of the bladder—the internal urethral sphincter. The external urethral sphincter is formed collectively by the overlying striated muscle fibers of the pelvic floor. The adult urinary bladder has a capacity of 400 to 600 ml. The bladder is innervated by efferent somatic, sympathetic, and parasympathetic fibers, whereas the visceral afferent fibers arise from the bladder wall (stretch receptors).
The parasympathetic fibers cause contraction of the detrusor and relaxation of the neck, permitting micturition. The sympathetic fibers, in contrast, influence the relaxation of the detrusor and close the internal urethral sphincter. These two systems are governed by spinal reflexes, which are regulated by two pontine brainstem centers, the pontine storage center and the pontine micturition center. The voluntary control of the bladder becomes fully developed by the first few years of life and involves the coordination among the frontal cortex, the pontine centers, and the spinal segments influencing bladder control. During micturition, two phases can be distinguished, the storage phase and the emptying phase.
The highly compliant bladder allows for storage of a large volume of urine without an increase in the intravesical pressure. The first urge to void is felt at a bladder volume of 150 ml. The tension receptors in the bladder wall are activated at a volume of approximately 300 ml, creating the sense of fullness. The activation of the tension receptors propagates signals that travel through the pelvic sensory nerves, arriving at the spinal cord, where they activate parasympathetic neurons. Activation of the parasympathetic neuron stimulates efferent pelvic nerves that lead to contraction of the detrusor muscle. Detrusor contractions last only a few seconds, substantially raising the intravesical pressure from a resting pressure of 40 mm H2O to a few hundred mm H2O. When the intravesical pressure reaches the voiding threshold, the detrusor contractions increase in intensity, frequency, and duration. This creates a complete and synchronous contraction of the detrusor muscle, allowing the bladder to empty quickly and efficiently.
If micturition is not desired or is inconvenient, afferent stimuli from the stretch receptors of the bladder along with the proprioceptive afferents of the urethra, penis, vagina, rectum perineum, and anal sphincters activate the sympathetic system and external urethral sphincter motor neurons and simultaneously inhibit the parasympathetic system. The final effect is to prevent micturition through the contraction of the sphincters and the relaxation of detrusor muscle. Furthermore cerebral input from the frontal cortex and the pontine centers also aids in inhibiting the parasympathetic neurons and activating the sympathetic pathways.
During, and shortly after, medical and surgical procedures, however, particularly those involving the use of general or spinal anesthesia, the above-described micturition process may be disrupted in a variety of ways. Traditionally, bladder catheterization has been employed during, and shortly after, medical and surgical procedures to address this issue. However, given today's increase in outpatient and fast-track surgical procedures, simpler and less invasive alternatives would be desirable.
Additionally, spinal cord injuries and other paralytic conditions may result in an atonic bladder or denervated voiding conditions. Moreover, UI also results from similar bladder and sphincter pathology, despite having no relationship to anesthesia or issues noted above related to need for catheterization.
Previously, attempts have been made to apply electrical stimulation to control the bladder and bowel. These previous attempts have predominantly focused on activation of the detrusor by sacral root, sacral plexus, or peripheral nerve stimulation, activating either motor or sensory nerves using various types of electrodes, such as cuff electrodes, subcutaneous electrodes, spiral electrodes, needle probes, dermal surface electrodes or surface mounted needles, and surgically implanted stimulators, to apply an electrical stimulus that may take the form of a pulse burst electrical stimulation or a continuous stimulation. Problems exist with these known types of therapies. The stimulation modalities used, in order to generate the requisite low frequency impulses required to achieve desirable results, may cause the patient to suffer pain, discomfort and/or tissue damage in the areas of electrical stimulation application and/or require invasive procedures to install the devices used. Also, they cannot accurately target deeper internal structures without such an invasive type surgical procedure.
Therefore, what is desired is a system and method for assisting with micturition in a patient with an anesthetized bladder, or suffering from spinal cord injuries and/or other paralytic conditions resulting in an atonic bladder or denervated voiding conditions, certain types of lower urinary tract obstructions, and pelvic floor muscle dysfunction as seen in urinary incontinence, which avoids the problems and medical complications associated with known systems and methods, already described, particularly the use of intermittent or indwelling catheterization, and also for simple ongoing control of urinary incontinence problems that may or may not require such catheter instrumentation.